Field of the Invention
This invention relates to structural concrete forming apparatus and methods.
Multi-story buildings are often constructed with poured concrete floor structures. In many cases, a sturdy subform is installed, several dome or pan-shaped forms are mounted on the subforms, and concrete is poured over the forms and allowed to partially set. The subform and the forms thereon are removed from the concrete and reinstalled for pouring another concrete structure. The same structure may be repeated several times for each story of the building, and many of the stories of the building may be identical, so that it is possible to utilize a single subform with several forms thereon to form a large part of the building.
A large part of the labor involved in constructing the poured concrete floors arises in handling of the several forms and subforms, that is, in moving them from one place to another and in accurately mounting the forms on the subforms for each pouring. If all of the forms could be bolted to the subform so that the entire apparatus could be moved and positioned as a single unit for each pouring of concrete, then the labor involved could be reduced significantly. However, difficulty is experienced in attempting to remove all of the forms simultaneously from set concrete. The forms are often stuck to the concrete, so that if the subform is lowered as a unit any stuck form may be broken. Actually, when several forms stick they may support the entire bay of forms and the subform, and if only one form at one side sticks, it may hold up only one end of the bay of forms and cause tilting of the assembly that causes the forms to bind as they start to move down. The forms can be freed by shaking them back and forth and by blowing air through holes provided in the forms as they are pulled down. However, great difficulties would be encountered in trying to simultaneously free all of the forms that are mounted on a subform as the subform is lowered.